Create Rotting-Oranges.cpp

Author: yuanfz98

August-LeetCoding-Challenge/09-Rotting-Oranges/Rotting-Oranges.cpp

@@ -0,0 +1,36 @@
+
+const int dx[4] = { -1, 0, 1, 0 };
+const int dy[4] = { 0, -1, 0, 1 };
+typedef pair<int,int> ip;
+class Solution {
+public:
+    int orangesRotting(vector<vector<int>>& grid) {
+        const int m=grid.size(), n=grid[0].size();
+        unordered_set<int> freshes;
+        queue<ip> rottens;
+        int r=0;
+        for(int i=0; i<m; ++i){
+            for(int j=0; j<n; ++j){
+                if(grid[i][j]){
+                    if(grid[i][j]==1) freshes.insert(n*i+j);
+                    else rottens.emplace(i,j);
+                }
+            }
+        }
+        while(!rottens.empty()){
+            for(int i=0, qsz=rottens.size(); i<qsz; ++i){
+                ip f=rottens.front(); rottens.pop(); auto [x,y] = f;
+                for(int j=0; j<4; ++j){
+                    int tox=dx[j]+x, toy=dy[j]+y, ind = n*tox+toy;
+                    if(tox>=0 && toy>=0 && tox<m && toy<n && freshes.count(ind)) 
+                        freshes.erase(ind), rottens.emplace(tox,toy);
+                }
+                
+            }
+            if(!rottens.empty())
+                ++r;           
+        }
+        if(!freshes.empty()) return -1;
+        else return r;
+    }
+};